Nickel-catalysed enantioselective reaction of secondary phosphine oxides and activated vinylcyclopropanes.

Activated vinylcyclopropanes can form zwitterionic π-allylmetal species in the presence of transition metals and are widely used in organic synthesis. A nickel-catalyzed asymmetric allylation of secondary phosphine oxides with vinylcyclopropanes was described. Tertiary phosphine oxide products could be obtained with up to 91% yield and 92% ee.

A Ni-catalyzed asymmetric C(sp)-P cross-coupling reaction for the synthesis of P-stereogenic alkynylphosphines.

Due to the high reactivity of the triple bond, P-stereogenic alkynylphosphines could be easily derivatized, serving as universal building blocks for structurally diverse phosphine compounds. However, the synthesis of alkynylphosphines via direct P-C bond formation was unprecedented. Here, we report an efficient method for the synthesis of P-stereogenic alkynylphosphines with high enantioselectivity via a Ni-catalyzed asymmetric cross-coupling reaction. The reaction could tolerate a variety of functional groups, affording products that can be converted into useful phosphine derivatives.

Ni-Catalyzed Enantioselective Allylic Alkylation of H-Phosphinates.

The asymmetric synthesis of P-stereogenic phosphinates through allylic alkylation of H-phosphinates has been developed. With H-phosphinates and allylic acetates as the starting materials, a variety of allylic P-chiral phosphinates were accessed in high enantioselectivities of up to 92% ee and generally high yields. In addition, a further study demonstrated the applicability of this protocol, including the scale-up synthesis and facile transformation of chiral products from phosphinates to phosphine oxides with organolithium reagents under mild reaction conditions.

Ni-Catalyzed Asymmetric Hydrophosphination of Unactivated Alkynes.

The practical synthesis of P-stereogenic tertiary phosphines, which have wide applications in asymmetric catalysis, materials, and pharmaceutical chemistry, represents a significant challenge. A regio- and enantioselective hydrophosphination using cheap and ubiquitous alkynes catalyzed by a nickel complex was designed, in which the toxic and air-sensitive secondary phosphines were prepared in situ from bench-stable secondary phosphine oxides. This methodology has been demonstrated with unprecedented substrate scope and functional group compatibility to afford electronically and structurally diversified P(III) compounds. The products could be easily converted into various precursors of bidentate ligands and organocatalysts, as well as a variety of transition-metal complexes containing both P- and metal-stereogenic centers.

Ni-Catalyzed Asymmetric Allylation of Secondary Phosphine Oxides.

A nickel-catalyzed asymmetric allylation of secondary phosphine oxides (SPO) for the synthesis of tertiary phosphine oxides (TPO) was realized with high enantioselectivity. The dynamic kinetic asymmetric transformation of SPO was accomplished in the presence of nickel complex. By elucidating the absolute configurations of the reacted SPO starting material and the TPO product, we confirmed that the allylation reaction proceeded through a P-stereo retention process. The protocol represents the first example of synthesizing P-stereogenic phosphine oxides by allylation reaction.